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Vance DJ, Basir S, Piazza CL, Willsey GG, Haque HME, Tremblay JM, Rudolph MJ, Muriuki B, Cavacini L, Weis DD, Shoemaker CB, Mantis NJ. Single-domain antibodies reveal unique borrelicidal epitopes on the Lyme disease vaccine antigen, outer surface protein A (OspA). Infect Immun 2024; 92:e0008424. [PMID: 38470113 PMCID: PMC11003225 DOI: 10.1128/iai.00084-24] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2024] [Accepted: 02/23/2024] [Indexed: 03/13/2024] Open
Abstract
Camelid-derived, single-domain antibodies (VHHs) have proven to be extremely powerful tools in defining the antigenic landscape of immunologically heterogeneous surface proteins. In this report, we generated a phage-displayed VHH library directed against the candidate Lyme disease vaccine antigen, outer surface protein A (OspA). Two alpacas were immunized with recombinant OspA serotype 1 from Borrelia burgdorferi sensu stricto strain B31, in combination with the canine vaccine RECOMBITEK Lyme containing lipidated OspA. The phage library was subjected to two rounds of affinity enrichment ("panning") against recombinant OspA, yielding 21 unique VHHs within two epitope bins, as determined through competition enzyme linked immunosorbent assays (ELISAs) with a panel of OspA-specific human monoclonal antibodies. Epitope refinement was conducted by hydrogen exchange-mass spectrometry. Six of the monovalent VHHs were expressed as human IgG1-Fc fusion proteins and shown to have functional properties associated with protective human monoclonal antibodies, including B. burgdorferi agglutination, outer membrane damage, and complement-dependent borreliacidal activity. The VHHs displayed unique reactivity profiles with the seven OspA serotypes associated with B. burgdorferi genospecies in the United States and Europe consistent with there being unique epitopes across OspA serotypes that should be considered when designing and evaluating multivalent Lyme disease vaccines.
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Affiliation(s)
- David J. Vance
- Division of Infectious Diseases, New York State Department of Health, Wadsworth Center, Albany, New York, USA
- Department of Biomedical Sciences, University at Albany, Albany, New York, USA
| | - Saiful Basir
- Department of Biomedical Sciences, University at Albany, Albany, New York, USA
| | - Carol Lyn Piazza
- Division of Infectious Diseases, New York State Department of Health, Wadsworth Center, Albany, New York, USA
| | - Graham G. Willsey
- Division of Infectious Diseases, New York State Department of Health, Wadsworth Center, Albany, New York, USA
| | | | - Jacque M. Tremblay
- Department of Infectious Disease and Global Health, Cummings School of Veterinary Medicine, Tufts University, North Grafton, Massachusetts, USA
| | | | - Beatrice Muriuki
- Department of Medicine, University of Massachusetts Chan School of Medicine, Worcester, Massachusetts, USA
| | - Lisa Cavacini
- Department of Medicine, University of Massachusetts Chan School of Medicine, Worcester, Massachusetts, USA
| | - David D. Weis
- Department of Chemistry, The University of Kansas, Lawrence, Kansas, USA
| | - Charles B. Shoemaker
- Department of Infectious Disease and Global Health, Cummings School of Veterinary Medicine, Tufts University, North Grafton, Massachusetts, USA
| | - Nicholas J. Mantis
- Division of Infectious Diseases, New York State Department of Health, Wadsworth Center, Albany, New York, USA
- Department of Biomedical Sciences, University at Albany, Albany, New York, USA
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2
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Vance DJ, Rudolph MJ, Davis SA, Mantis NJ. Structural Basis of Antibody-Mediated Inhibition of Ricin Toxin Attachment to Host Cells. Biochemistry 2023; 62:3181-3187. [PMID: 37903428 DOI: 10.1021/acs.biochem.3c00480] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/01/2023]
Abstract
Monoclonal antibodies, JB4 and SylH3, neutralize ricin toxin (RT) by inhibiting the galactose-specific lectin activity of the B subunit of the toxin (RTB), which is required for cell attachment and entry. It is not immediately apparent how the antibodies accomplish this feat, considering that RTB consists of two globular domains (D1, D2) each divided into three homologous subdomains (α, β, γ) with the two functional galactosyl-specific carbohydrate recognition domains (CRDs) situated on opposite poles (subdomains 1α and 2γ). Here, we report the X-ray crystal structures of JB4 and SylH3 Fab fragments bound to RTB in the context of RT. The structures revealed that neither Fab obstructed nor induced detectable conformational alterations in subdomains 1α or 2γ. Rather, JB4 and SylH3 Fabs recognize nearly identical epitopes within an ancillary carbohydrate recognition pocket located in subdomain 1β. Despite limited amino acid sequence similarity between SylH3 and JB4 Fabs, each paratope inserts a Phe side chain from the heavy (H) chain complementarity determining region (CDR3) into the 1β CRD pocket, resulting in local aromatic stacking interactions that potentially mimic a ligand interaction. Reconciling the fact that stoichiometric amounts of SylH3 and JB4 are sufficient to disarm RTB's lectin activity without evidence of allostery, we propose that subdomain 1β functions as a "coreceptor" required to stabilize glycan interactions principally mediated by subdomains 1α and 2γ. Further investigation into subdomain 1β will yield fundamental insights into the large family of R-type lectins and open novel avenues for countermeasures aimed at preventing toxin uptake into vulnerable tissues and cells.
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Affiliation(s)
- David J Vance
- Division of Infectious Diseases, Wadsworth Center, New York State Department of Health, Albany, New York 12208, United States
| | - Michael J Rudolph
- New York Structural Biology Center, New York, New York 10027, United States
| | - Simon A Davis
- New York Structural Biology Center, New York, New York 10027, United States
| | - Nicholas J Mantis
- Division of Infectious Diseases, Wadsworth Center, New York State Department of Health, Albany, New York 12208, United States
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3
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Rudolph MJ, Davis SA, Haque HME, Ejemel M, Cavacini LA, Vance DJ, Willsey GG, Piazza CL, Weis DD, Wang Y, Mantis NJ. Structure of a transmission blocking antibody in complex with Outer surface protein A from the Lyme disease spirochete, Borreliella burgdorferi. Proteins 2023; 91:1463-1470. [PMID: 37455569 PMCID: PMC10592432 DOI: 10.1002/prot.26549] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2023] [Revised: 06/23/2023] [Accepted: 06/28/2023] [Indexed: 07/18/2023]
Abstract
319-44 is a human monoclonal antibody capable of passively protecting mice against tick-mediated infection with Borreliella burgdorferi, the bacterial genospecies responsible for Lyme disease in North America. In vitro, 319-44 has complement-dependent borreliacidal activity and spirochete agglutinating properties. Here, we report the 2.2 Å-resolution crystal structure of 319-44 Fab fragments in complex with Outer surface protein A (OspA), the ~30 kDa lipoprotein that was the basis of the first-generation Lyme disease vaccine approved in the United States. The 319-44 epitope is focused on OspA β-strands 19, 20, and 21, and the loops between β-strands 16-17, 18-19, and 20-21. Contact with loop 20-21 explains competition with LA-2, the murine monoclonal antibody used to estimate serum borreliacidal activities in the first-generation Lyme disease vaccine clinical trials. A high-resolution B-cell epitope map of OspA will accelerate structure-based design of second generation OspA-based vaccines.
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Affiliation(s)
| | | | | | | | | | - David J. Vance
- Division of Infectious Diseases, Wadsworth Center, New York State Department of Health, Albany, NY 12208
| | - Graham G. Willsey
- Division of Infectious Diseases, Wadsworth Center, New York State Department of Health, Albany, NY 12208
| | - Carol Lyn Piazza
- Division of Infectious Diseases, Wadsworth Center, New York State Department of Health, Albany, NY 12208
| | - David D. Weis
- Department of Chemistry, University of Kansas, Lawrence, KS 66045
| | | | - Nicholas J Mantis
- Division of Infectious Diseases, Wadsworth Center, New York State Department of Health, Albany, NY 12208
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4
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Rudolph MJ, Davis SA, Haque HME, Weis DD, Vance DJ, Piazza CL, Ejemel M, Cavacini L, Wang Y, Mbow ML, Gilmore RD, Mantis NJ. Structural Elucidation of a Protective B Cell Epitope on Outer Surface Protein C (OspC) of the Lyme Disease Spirochete, Borreliella burgdorferi. mBio 2023; 14:e0298122. [PMID: 36976016 PMCID: PMC10128040 DOI: 10.1128/mbio.02981-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/29/2023] Open
Abstract
Outer surface protein C (OspC) plays a pivotal role in mediating tick-to-host transmission and infectivity of the Lyme disease spirochete, Borreliella burgdorferi. OspC is a helical-rich homodimer that interacts with tick salivary proteins, as well as components of the mammalian immune system. Several decades ago, it was shown that the OspC-specific monoclonal antibody, B5, was able to passively protect mice from experimental tick-transmitted infection by B. burgdorferi strain B31. However, B5's epitope has never been elucidated, despite widespread interest in OspC as a possible Lyme disease vaccine antigen. Here, we report the crystal structure of B5 antigen-binding fragments (Fabs) in complex with recombinant OspC type A (OspCA). Each OspC monomer within the homodimer was bound by a single B5 Fab in a side-on orientation, with contact points along OspC's α-helix 1 and α-helix 6, as well as interactions with the loop between α-helices 5 and 6. In addition, B5's complementarity-determining region (CDR) H3 bridged the OspC-OspC' homodimer interface, revealing the quaternary nature of the protective epitope. To provide insight into the molecular basis of B5 serotype specificity, we solved the crystal structures of recombinant OspC types B and K and compared them to OspCA. This study represents the first structure of a protective B cell epitope on OspC and will aid in the rational design of OspC-based vaccines and therapeutics for Lyme disease. IMPORTANCE The spirochete Borreliella burgdorferi is a causative agent of Lyme disease, the most common tickborne disease in the United States. The spirochete is transmitted to humans during the course of a tick taking a bloodmeal. After B. burgdorferi is deposited into the skin of a human host, it replicates locally and spreads systemically, often resulting in clinical manifestations involving the central nervous system, joints, and/or heart. Antibodies directed against B. burgdorferi's outer surface protein C (OspC) are known to block tick-to-host transmission, as well as dissemination of the spirochete within a mammalian host. In this report, we reveal the first atomic structure of one such antibody in complex with OspC. Our results have implications for the design of a Lyme disease vaccine capable of interfering with multiple stages in B. burgdorferi infection.
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Affiliation(s)
| | - Simon A Davis
- New York Structural Biology Center, New York, New York, USA
| | - H M Emranul Haque
- Department of Chemistry, University of Kansas, Lawrence, Kansas, USA
| | - David D Weis
- Department of Chemistry, University of Kansas, Lawrence, Kansas, USA
| | - David J Vance
- Division of Infectious Diseases, Wadsworth Center, New York State Department of Health, Albany, New York, USA
| | - Carol Lyn Piazza
- Division of Infectious Diseases, Wadsworth Center, New York State Department of Health, Albany, New York, USA
| | - Monir Ejemel
- MassBiologics of the University of Massachusetts Chan Medical School, Boston, Massachusetts, USA
| | - Lisa Cavacini
- MassBiologics of the University of Massachusetts Chan Medical School, Boston, Massachusetts, USA
| | - Yang Wang
- MassBiologics of the University of Massachusetts Chan Medical School, Boston, Massachusetts, USA
| | - M Lamine Mbow
- Division of Vector Borne Diseases, National Center for Emerging and Zoonotic Infectious Diseases, Centers for Disease Control and Prevention, Fort Collins, Colorado, USA
| | - Robert D Gilmore
- Division of Vector Borne Diseases, National Center for Emerging and Zoonotic Infectious Diseases, Centers for Disease Control and Prevention, Fort Collins, Colorado, USA
| | - Nicholas J Mantis
- Division of Infectious Diseases, Wadsworth Center, New York State Department of Health, Albany, New York, USA
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5
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Haque HME, Ejemel M, Vance DJ, Willsey G, Rudolph MJ, Cavacini LA, Wang Y, Mantis NJ, Weis DD. Human B Cell Epitope Map of the Lyme Disease Vaccine Antigen, OspA. ACS Infect Dis 2022; 8:2515-2528. [PMID: 36350351 DOI: 10.1021/acsinfecdis.2c00346] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
The Lyme disease (LD) vaccine formerly approved for use in the United States consisted of recombinant outer surface protein A (OspA) from Borrelia burgdorferi sensu stricto (ss), the bacterial genospecies responsible for the vast majority of LD in North America. OspA is an ∼30 kDa lipoprotein made up of 21 antiparallel β-strands and a C-terminal α-helix. In clinical trials, protection against LD following vaccination correlated with serum antibody titers against a single epitope near the C-terminus of OspA, as defined by the mouse monoclonal antibody (MAb), LA-2. However, the breadth of the human antibody response to OspA following vaccination remains undefined even as next-generation multivalent OspA-based vaccines are under development. In this report, we employed hydrogen exchange-mass spectrometry (HX-MS) to localize the epitopes recognized by a unique panel of OspA human MAbs, including four shown to passively protect mice against experimental B. burgdorferi infection and one isolated from a patient with antibiotic refractory Lyme arthritis. The epitopes grouped into three spatially distinct bins that, together, encompass more than half the surface-exposed area of OspA. The bins corresponded to OspA β-strands 8-10 (bin 1), 11-13 (bin 2), and 16-20 plus the C-terminal α-helix (bin 3). Bin 3 was further divided into sub-bins relative to LA-2's epitope. MAbs with complement-dependent borreliacidal activity, as well as B. burgdorferi transmission-blocking activity in the mouse model were found within each bin. Therefore, the resulting B cell epitope map encompasses functionally important targets on OspA that likely contribute to immunity to B. burgdorferi.
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Affiliation(s)
- H M Emranul Haque
- Department of Chemistry, University of Kansas, Lawrence, Kansas66045, United States
| | - Monir Ejemel
- MassBiologics, Boston, Massachusetts02126, United States
| | - David J Vance
- Division of Infectious Diseases, Wadsworth Center, New York State Department of Health, Albany, New York12208, United States
| | - Graham Willsey
- Division of Infectious Diseases, Wadsworth Center, New York State Department of Health, Albany, New York12208, United States
| | - Michael J Rudolph
- New York Structural Biology Center, New York, New York10027, United States
| | | | - Yang Wang
- MassBiologics, Boston, Massachusetts02126, United States
| | - Nicholas J Mantis
- Division of Infectious Diseases, Wadsworth Center, New York State Department of Health, Albany, New York12208, United States
| | - David D Weis
- Department of Chemistry, University of Kansas, Lawrence, Kansas66045, United States
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6
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Czajka TF, Vance DJ, Davis S, Rudolph MJ, Mantis NJ. Single-domain antibodies neutralize ricin toxin intracellularly by blocking access to ribosomal P-stalk proteins. J Biol Chem 2022; 298:101742. [PMID: 35182523 PMCID: PMC8941211 DOI: 10.1016/j.jbc.2022.101742] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2022] [Revised: 02/10/2022] [Accepted: 02/14/2022] [Indexed: 12/27/2022] Open
Abstract
During ricin intoxication in mammalian cells, ricin's enzymatic (RTA) and binding (RTB) subunits disassociate in the endoplasmic reticulum. RTA is then translocated into the cytoplasm where, by virtue of its ability to depurinate a conserved residue within the sarcin-ricin loop (SRL) of 28S rRNA, it functions as a ribosome-inactivating protein. It has been proposed that recruitment of RTA to the SRL is facilitated by ribosomal P-stalk proteins, whose C-terminal domains interact with a cavity on RTA normally masked by RTB; however, evidence that this interaction is critical for RTA activity within cells is lacking. Here, we characterized a collection of single-domain antibodies (VHHs) whose epitopes overlap with the P-stalk binding pocket on RTA. The crystal structures of three such VHHs (V9E1, V9F9, and V9B2) in complex with RTA revealed not only occlusion of the ribosomal P-stalk binding pocket but also structural mimicry of C-terminal domain peptides by complementarity-determining region 3. In vitro assays confirmed that these VHHs block RTA-P-stalk peptide interactions and protect ribosomes from depurination. Moreover, when expressed as "intrabodies," these VHHs rendered cells resistant to ricin intoxication. One VHH (V9F6), whose epitope was structurally determined to be immediately adjacent to the P-stalk binding pocket, was unable to neutralize ricin within cells or protect ribosomes from RTA in vitro. These findings are consistent with the recruitment of RTA to the SRL by ribosomal P-stalk proteins as a requisite event in ricin-induced ribosome inactivation.
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Affiliation(s)
- Timothy F Czajka
- Department of Biomedical Sciences, University at Albany, Albany, New York, USA
| | - David J Vance
- Department of Biomedical Sciences, University at Albany, Albany, New York, USA; Division of Infectious Diseases, Wadsworth Center, New York State Department of Health, Albany, New York, USA
| | - Simon Davis
- New York Structural Biology Center, New York, New York, USA
| | | | - Nicholas J Mantis
- Department of Biomedical Sciences, University at Albany, Albany, New York, USA; Division of Infectious Diseases, Wadsworth Center, New York State Department of Health, Albany, New York, USA.
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7
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Rudolph MJ, Poon AY, Kavaliauskiene S, Myrann AG, Reynolds-Peterson C, Davis SA, Sandvig K, Vance DJ, Mantis NJ. Structural Analysis of Toxin-Neutralizing, Single-Domain Antibodies that Bridge Ricin's A-B Subunit Interface. J Mol Biol 2021; 433:167086. [PMID: 34089718 DOI: 10.1016/j.jmb.2021.167086] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2021] [Revised: 05/18/2021] [Accepted: 05/27/2021] [Indexed: 01/20/2023]
Abstract
Ricin toxin kills mammalian cells with notorious efficiency. The toxin's B subunit (RTB) is a Gal/GalNAc-specific lectin that attaches to cell surfaces and promotes retrograde transport of ricin's A subunit (RTA) to the trans Golgi network (TGN) and endoplasmic reticulum (ER). RTA is liberated from RTB in the ER and translocated into the cell cytoplasm, where it functions as a ribosome-inactivating protein. While antibodies against ricin's individual subunits have been reported, we now describe seven alpaca-derived, single-domain antibodies (VHHs) that span the RTA-RTB interface, including four Tier 1 VHHs with IC50 values <1 nM. Crystal structures of each VHH bound to native ricin holotoxin revealed three different binding modes, based on contact with RTA's F-G loop (mode 1), RTB's subdomain 2γ (mode 2) or both (mode 3). VHHs in modes 2 and 3 were highly effective at blocking ricin attachment to HeLa cells and immobilized asialofetuin, due to framework residues (FR3) that occupied the 2γ Gal/GalNAc-binding pocket and mimic ligand. The four Tier 1 VHHs also interfered with intracellular functions of RTB, as they neutralized ricin in a post-attachment cytotoxicity assay (e.g., the toxin was bound to cell surfaces before antibody addition) and reduced the efficiency of toxin transport to the TGN. We conclude that the RTA-RTB interface is a target of potent toxin-neutralizing antibodies that interfere with both extracellular and intracellular events in ricin's cytotoxic pathway.
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Affiliation(s)
| | - Amanda Y Poon
- Department of Biomedical Sciences, University at Albany, Albany, NY, USA; Division of Infectious Diseases, Wadsworth Center, New York State Department of Health, Albany, NY, USA
| | - Simona Kavaliauskiene
- Department of Molecular Cell Biology, Institute for Cancer Research, The Norwegian Radium Hospital, Oslo University Hospital, Montebello, Oslo, Norway
| | - Anne Grethe Myrann
- Department of Molecular Cell Biology, Institute for Cancer Research, The Norwegian Radium Hospital, Oslo University Hospital, Montebello, Oslo, Norway
| | - Claire Reynolds-Peterson
- Division of Infectious Diseases, Wadsworth Center, New York State Department of Health, Albany, NY, USA
| | - Simon A Davis
- New York Structural Biology Center, New York, NY, USA
| | - Kirsten Sandvig
- Department of Molecular Cell Biology, Institute for Cancer Research, The Norwegian Radium Hospital, Oslo University Hospital, Montebello, Oslo, Norway; Department of Biosciences, University of Oslo, Oslo, Norway
| | - David J Vance
- Division of Infectious Diseases, Wadsworth Center, New York State Department of Health, Albany, NY, USA
| | - Nicholas J Mantis
- Division of Infectious Diseases, Wadsworth Center, New York State Department of Health, Albany, NY, USA.
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8
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Abstract
Camelid-derived and synthetic single-domain antibodies (sdAbs) are emerging as potent weapons against the novel coronavirus, SARS-CoV-2. sdAbs are small, compact, thermostable immunoglobulin elements capable of binding targets with subnanomolar affinities. By leveraging the power of phage- and yeast surface-display technologies, rare sdAbs can be isolated from highly diverse and complex antibody libraries. Once in hand, sdAbs can be engineered to improve binding affinity, avidity, target specificities, and biodistribution. In this Opinion piece we highlight a series of sophisticated studies describing the identification of ultrapotent sdAbs directed against the receptor-binding domain (RBD) of the SARS-CoV-2 Spike protein. We discuss the possible applications of these antibodies in the global fight against COVID-19.
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Affiliation(s)
- Timothy F Czajka
- Department of Biomedical Sciences, University at Albany, Albany, NY 12201, USA
| | - David J Vance
- Division of Infectious Diseases, Wadsworth Center, New York State Department of Health, Albany, NY 12208, USA
| | - Nicholas J Mantis
- Department of Biomedical Sciences, University at Albany, Albany, NY 12201, USA; Division of Infectious Diseases, Wadsworth Center, New York State Department of Health, Albany, NY 12208, USA.
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9
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Vance DJ, Poon AY, Mantis NJ. Sites of vulnerability on ricin B chain revealed through epitope mapping of toxin-neutralizing monoclonal antibodies. PLoS One 2020; 15:e0236538. [PMID: 33166282 PMCID: PMC7652295 DOI: 10.1371/journal.pone.0236538] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2020] [Accepted: 10/26/2020] [Indexed: 12/16/2022] Open
Abstract
Ricin toxin's B subunit (RTB) is a multifunctional galactose (Gal)-/N-acetylgalactosamine (GalNac)-specific lectin that promotes uptake and intracellular trafficking of ricin's ribosome-inactivating subunit (RTA) into mammalian cells. Structurally, RTB consists of two globular domains (RTB-D1, RTB-D2), each divided into three homologous sub-domains (α, β, γ). The two carbohydrate recognition domains (CRDs) are situated on opposite sides of RTB (sub-domains 1α and 2γ) and function non-cooperatively. Previous studies have revealed two distinct classes of toxin-neutralizing, anti-RTB monoclonal antibodies (mAbs). Type I mAbs, exemplified by SylH3, inhibit (~90%) toxin attachment to cell surfaces, while type II mAbs, epitomized by 24B11, interfere with intracellular toxin transport between the plasma membrane and the trans-Golgi network (TGN). Localizing the epitopes recognized by these two classes of mAbs has proven difficult, in part because of RTB's duplicative structure. To circumvent this problem, RTB-D1 and RTB-D2 were expressed as pIII fusion proteins on the surface of filamentous phage M13 and subsequently used as "bait" in mAb capture assays. We found that SylH3 captured RTB-D1 (but not RTB-D2) in a dose-dependent manner, while 24B11 captured RTB-D2 (but not RTB-D1) in a dose-dependent manner. We confirmed these domain assignments by competition studies with an additional 8 RTB-specific mAbs along with a dozen a single chain antibodies (VHHs). Collectively, these results demonstrate that type I and type II mAbs segregate on the basis of domain specificity and suggest that RTB's two domains may contribute to distinct steps in the intoxication pathway.
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Affiliation(s)
- David J. Vance
- Division of Infectious Disease, New York State Department of Health,Wadsworth Center, Albany, NY, United States of America
- * E-mail: (DJV); (NJM)
| | - Amanda Y. Poon
- Department of Biomedical Sciences, University at Albany School of Public Health, Albany, NY, United States of America
| | - Nicholas J. Mantis
- Division of Infectious Disease, New York State Department of Health,Wadsworth Center, Albany, NY, United States of America
- Department of Biomedical Sciences, University at Albany School of Public Health, Albany, NY, United States of America
- * E-mail: (DJV); (NJM)
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10
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Abstract
The two banana prawns Penaeus merguiensis and P. indicus are arguably the most commercially important species of penaeid prawns in the tropical and sub-tropical Indo-West Pacific region. They are fecund, short-lived, and have a complex life history involving offshore spawning, inshore mangrove-lined nursery grounds, and migrations between the two locations. We have reviewed and assessed published research on: the fisheries and aquaculture; taxonomy and identification; distribution and habitat preferences; growth; mortality; food and feeding; predation, and the importance of the mangrove habitat to banana prawns. We have examined the life history patterns of these two banana prawns and the many environmental and biological factors that affect different life history stages, often resulting in large interannual variations in abundances of adult prawns and commercial catches. We have also reviewed research on the ecosystem relationships involving these prawns, including fishery impacts on the environment and other species caught as bycatch. In reviewing the published information on factors affecting recruitment dynamics and variability, we have sometimes found contrasting and confounding results, suggesting that these factors are not yet fully understood. Therefore, for each aspect of the prawns' biology we have pointed to areas with incomplete or conflicted understanding, which will hopefully guide future research on these extremely valuable prawn species.
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Affiliation(s)
- David J Vance
- CSIRO Oceans & Atmosphere, Queensland BioSciences Precinct, St Lucia, QLD, Australia.
| | - Peter C Rothlisberg
- CSIRO Oceans & Atmosphere, Queensland BioSciences Precinct, St Lucia, QLD, Australia
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11
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Rudolph MJ, Czajka TF, Davis SA, Thi Nguyen CM, Li XP, Tumer NE, Vance DJ, Mantis NJ. Intracellular Neutralization of Ricin Toxin by Single-domain Antibodies Targeting the Active Site. J Mol Biol 2020; 432:1109-1125. [PMID: 31931008 PMCID: PMC7066583 DOI: 10.1016/j.jmb.2020.01.006] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2019] [Revised: 12/16/2019] [Accepted: 01/02/2020] [Indexed: 02/06/2023]
Abstract
The extreme potency of the plant toxin, ricin, is due to its enzymatic subunit, RTA, which inactivates mammalian ribosomes with near-perfect efficiency. Here we characterized, at the functional and structural levels, seven alpaca single-domain antibodies (VHHs) previously reported to recognize epitopes in proximity to RTA's active site. Three of the VHHs, V2A11, V8E6, and V2G10, were potent inhibitors of RTA in vitro and protected Vero cells from ricin when expressed as intracellular antibodies ("intrabodies"). Crystal structure analysis revealed that the complementarity-determining region 3 (CDR3) elements of V2A11 and V8E6 penetrate RTA's active site and interact with key catalytic residues. V2G10, by contrast, sits atop the enzymatic pocket and occludes substrate accessibility. The other four VHHs also penetrated/occluded RTA's active site, but lacked sufficient binding affinities to outcompete RTA-ribosome interactions. Intracellular delivery of high-affinity, single-domain antibodies may offer a new avenue in the development of countermeasures against ricin toxin.toxin, antibody, structure, intracellular.
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Affiliation(s)
- Michael J Rudolph
- New York Structural Biology Center, New York, NY 10027, United States.
| | - Timothy F Czajka
- Division of Infectious Diseases, Wadsworth Center, New York State Department of Health, Albany, NY, 12208, United States; Department of Biomedical Sciences, University at Albany, Albany, NY 12201, United States
| | - Simon A Davis
- New York Structural Biology Center, New York, NY 10027, United States
| | - Chi My Thi Nguyen
- New York Structural Biology Center, New York, NY 10027, United States
| | - Xiao-Ping Li
- Department of Plant Biology, Rutgers, The State University of New Jersey, New Brunswick, NJ 08901, United States
| | - Nilgun E Tumer
- Department of Plant Biology, Rutgers, The State University of New Jersey, New Brunswick, NJ 08901, United States
| | - David J Vance
- Division of Infectious Diseases, Wadsworth Center, New York State Department of Health, Albany, NY, 12208, United States
| | - Nicholas J Mantis
- Division of Infectious Diseases, Wadsworth Center, New York State Department of Health, Albany, NY, 12208, United States; Department of Biomedical Sciences, University at Albany, Albany, NY 12201, United States.
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12
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Van Slyke G, Angalakurthi SK, Toth RT, Vance DJ, Rong Y, Ehrbar D, Shi Y, Middaugh CR, Volkin DB, Weis DD, Mantis NJ. Fine-Specificity Epitope Analysis Identifies Contact Points on Ricin Toxin Recognized by Protective Monoclonal Antibodies. Immunohorizons 2018; 2:262-273. [PMID: 30766971 DOI: 10.4049/immunohorizons.1800042] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Ricin is a fast-acting protein toxin classified by the Centers for Disease Control and Prevention as a biothreat agent. In this report, we describe five new mouse mAbs directed against an immunodominant region, so-called epitope cluster II, on the surface of ricin's ribosome-inactivating enzymatic subunit A (RTA). The five mAbs were tested alongside four previously described cluster II-specific mAbs for their capacity to passively protect mice against 10× LD50 ricin challenge by injection. Only three of the mAbs (LE4, PH12, and TB12) afforded protection over the 7-d study period. Neither binding affinity nor in vitro toxin-neutralizing activity could fully account for LE4, PH12, and TB12's potent in vivo activity relative to the other six mAbs. However, epitope mapping studies by hydrogen exchange-mass spectrometry revealed that LE4, PH12, and TB12 shared common contact points on RTA corresponding to RTA α-helices D and E and β-strands d and e located on the back side of RTA relative to the active site. The other six mAbs recognized overlapping epitopes on RTA, but none shared the same hydrogen exchange-mass spectrometry profile as LE4, PH12, and TB12. A high-density competition ELISA with a panel of ricin-specific, single-domain camelid Abs indicated that even though LE4, PH12, and TB12 make contact with similar secondary motifs, they likely approach RTA from different angles. These results underscore how subtle differences in epitope specificity can significantly impact Ab functionality in vivo. ImmunoHorizons, 2018, 2: 262-273.
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Affiliation(s)
- Greta Van Slyke
- Division of Infectious Diseases, Wadsworth Center, New York State Department of Health, Albany, NY 12208
| | - Siva Krishna Angalakurthi
- Macromolecule and Vaccine Stabilization Center, Department of Pharmaceutical Chemistry, University of Kansas, Lawrence, KS 66045
| | - Ronald T Toth
- Macromolecule and Vaccine Stabilization Center, Department of Pharmaceutical Chemistry, University of Kansas, Lawrence, KS 66045
| | - David J Vance
- Division of Infectious Diseases, Wadsworth Center, New York State Department of Health, Albany, NY 12208
| | - Yinghui Rong
- Division of Infectious Diseases, Wadsworth Center, New York State Department of Health, Albany, NY 12208
| | - Dylan Ehrbar
- Division of Infectious Diseases, Wadsworth Center, New York State Department of Health, Albany, NY 12208
| | - Yuqi Shi
- Department of Chemistry, University of Kansas, Lawrence, KS 66045
| | - C Russell Middaugh
- Macromolecule and Vaccine Stabilization Center, Department of Pharmaceutical Chemistry, University of Kansas, Lawrence, KS 66045
| | - David B Volkin
- Macromolecule and Vaccine Stabilization Center, Department of Pharmaceutical Chemistry, University of Kansas, Lawrence, KS 66045
| | - David D Weis
- Department of Chemistry, University of Kansas, Lawrence, KS 66045
| | - Nicholas J Mantis
- Division of Infectious Diseases, Wadsworth Center, New York State Department of Health, Albany, NY 12208
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13
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Rudolph MJ, Vance DJ, Kelow S, Angalakurthi SK, Nguyen S, Davis SA, Rong Y, Middaugh CR, Weis DD, Dunbrack R, Karanicolas J, Mantis NJ. Contribution of an unusual CDR2 element of a single domain antibody in ricin toxin binding affinity and neutralizing activity. Protein Eng Des Sel 2018; 31:277-287. [PMID: 30265352 PMCID: PMC6277176 DOI: 10.1093/protein/gzy022] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2018] [Accepted: 08/03/2018] [Indexed: 11/13/2022] Open
Abstract
Ricin toxin's enzymatic subunit (RTA) has been subjected to intensive B cell epitope mapping studies using a combination of competition ELISAs, hydrogen exchange-mass spectrometry and X-ray crystallography. Those studies identified four spatially distinct clusters (I-IV) of toxin-neutralizing epitopes on the surface of RTA. Here we describe A9, a new single domain camelid antibody (VHH) that was proposed to recognize a novel epitope on RTA that straddles clusters I and III. The X-ray crystal structure of A9 bound to RTA (2.6 Å resolution) revealed extensive antibody contact with RTA's β-strand h (732 Å2 buried surface area; BSA), along with limited engagement with α-helix D (90 Å2) and α-helix C (138 Å2). Collectively, these contacts explain the overlap between epitope clusters I and III, as identified by competition ELISA. However, considerable binding affinity, and, consequently, toxin-neutralizing activity of A9 is mediated by an unusual CDR2 containing five consecutive Gly residues that interact with α-helix B (82 Å2), a known neutralizing hotspot on RTA. Removal of a single Gly residue from the penta-glycine stretch in CDR2 reduced A9's binding affinity by 10-fold and eliminated toxin-neutralizing activity. Computational modeling indicates that removal of a Gly from CDR2 does not perturb contact with RTA per se, but results in the loss of an intramolecular hydrogen bond network involved in stabilizing CDR2 in the unbound state. These results reveal a novel configuration of a CDR2 element involved in neutralizing ricin toxin.
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Affiliation(s)
| | - David J Vance
- Division of Infectious Diseases, Wadsworth Center, New York State Department of Health, Albany, NY, USA
| | - Simon Kelow
- Department of Biochemistry and Molecular Biophysics Graduate Group, University of Pennsylvania, Philadelphia, PA, USA
| | - Siva Krishna Angalakurthi
- Department of Pharmaceutical Chemistry and Macromolecule and Vaccine Stabilization Center, University of Kansas, Lawrence, KS, USA
| | - Sophie Nguyen
- New York Structural Biology Center, New York, NY, USA
| | - Simon A Davis
- New York Structural Biology Center, New York, NY, USA
| | - Yinghui Rong
- Division of Infectious Diseases, Wadsworth Center, New York State Department of Health, Albany, NY, USA
| | - C Russell Middaugh
- Department of Pharmaceutical Chemistry and Macromolecule and Vaccine Stabilization Center, University of Kansas, Lawrence, KS, USA
| | - David D Weis
- Department of Chemistry and Ralph Adams Institute for Bioanalytical Chemistry, University of Kansas, Lawrence, KS, USA
| | - Roland Dunbrack
- Institute for Cancer Research, Fox Chase Cancer Center, Philadelphia, PA, USA
| | - John Karanicolas
- Institute for Cancer Research, Fox Chase Cancer Center, Philadelphia, PA, USA
| | - Nicholas J Mantis
- Division of Infectious Diseases, Wadsworth Center, New York State Department of Health, Albany, NY, USA
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14
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Vance DJ, Tremblay JM, Rong Y, Angalakurthi SK, Volkin DB, Middaugh CR, Weis DD, Shoemaker CB, Mantis NJ. High-Resolution Epitope Positioning of a Large Collection of Neutralizing and Nonneutralizing Single-Domain Antibodies on the Enzymatic and Binding Subunits of Ricin Toxin. Clin Vaccine Immunol 2017; 24:e00236-17. [PMID: 29021300 PMCID: PMC5717184 DOI: 10.1128/cvi.00236-17] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/08/2017] [Accepted: 10/02/2017] [Indexed: 01/05/2023]
Abstract
We previously produced a heavy-chain-only antibody (Ab) VH domain (VHH)-displayed phage library from two alpacas that had been immunized with ricin toxoid and nontoxic mixtures of the enzymatic ricin toxin A subunit (RTA) and binding ricin toxin B subunit (RTB) (D. J. Vance, J. M. Tremblay, N. J. Mantis, and C. B. Shoemaker, J Biol Chem 288:36538-36547, 2013, https://doi.org/10.1074/jbc.M113.519207). Initial and subsequent screens of that library by direct enzyme-linked immunosorbent assay (ELISA) yielded more than two dozen unique RTA- and RTB-specific VHHs, including 10 whose structures were subsequently solved in complex with RTA. To generate a more complete antigenic map of ricin toxin and to define the epitopes associated with toxin-neutralizing activity, we subjected the VHH-displayed phage library to additional "pannings" on both receptor-bound ricin and antibody-captured ricin. We now report the full-length DNA sequences, binding affinities, and neutralizing activities of 68 unique VHHs: 31 against RTA, 33 against RTB, and 4 against ricin holotoxin. Epitope positioning was achieved through cross-competition ELISAs performed with a panel of monoclonal antibodies (MAbs) and verified, in some instances, with hydrogen-deuterium exchange mass spectrometry. The 68 VHHs grouped into more than 20 different competition bins. The RTA-specific VHHs with strong toxin-neutralizing activities were confined to bins that overlapped two previously identified neutralizing hot spots, termed clusters I and II. The four RTB-specific VHHs with potent toxin-neutralizing activity grouped within three adjacent bins situated at the RTA-RTB interface near cluster II. These results provide important insights into epitope interrelationships on the surface of ricin and delineate regions of vulnerability that can be exploited for the purpose of vaccine and therapeutic development.
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Affiliation(s)
- David J Vance
- Division of Infectious Disease, Wadsworth Center, New York State Department of Health, Albany, New York, USA
| | - Jacqueline M Tremblay
- Department of Infectious Disease and Global Health, Tufts Cummings School of Veterinary Medicine, North Grafton, Massachusetts, USA
| | - Yinghui Rong
- Division of Infectious Disease, Wadsworth Center, New York State Department of Health, Albany, New York, USA
| | - Siva Krishna Angalakurthi
- Department of Pharmaceutical Chemistry, Macromolecule and Vaccine Stabilization Center, University of Kansas, Lawrence, Kansas, USA
| | - David B Volkin
- Department of Pharmaceutical Chemistry, Macromolecule and Vaccine Stabilization Center, University of Kansas, Lawrence, Kansas, USA
| | - C Russell Middaugh
- Department of Pharmaceutical Chemistry, Macromolecule and Vaccine Stabilization Center, University of Kansas, Lawrence, Kansas, USA
| | - David D Weis
- Department of Chemistry, University of Kansas, Lawrence, Kansas, USA
| | - Charles B Shoemaker
- Department of Infectious Disease and Global Health, Tufts Cummings School of Veterinary Medicine, North Grafton, Massachusetts, USA
| | - Nicholas J Mantis
- Division of Infectious Disease, Wadsworth Center, New York State Department of Health, Albany, New York, USA
- Department of Biomedical Sciences, University at Albany, SUNY, Albany, New York, USA
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15
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Bazzoli A, Vance DJ, Rudolph MJ, Rong Y, Angalakurthi SK, Toth RT, Middaugh CR, Volkin DB, Weis DD, Karanicolas J, Mantis NJ. Using homology modeling to interrogate binding affinity in neutralization of ricin toxin by a family of single domain antibodies. Proteins 2017; 85:1994-2008. [PMID: 28718923 DOI: 10.1002/prot.25353] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2017] [Revised: 07/13/2017] [Accepted: 07/14/2017] [Indexed: 12/12/2022]
Abstract
In this report we investigated, within a group of closely related single domain camelid antibodies (VH Hs), the relationship between binding affinity and neutralizing activity as it pertains to ricin, a fast-acting toxin and biothreat agent. The V1C7-like VH Hs (V1C7, V2B9, V2E8, and V5C1) are similar in amino acid sequence, but differ in their binding affinities and toxin-neutralizing activities. Using the X-ray crystal structure of V1C7 in complex with ricin's enzymatic subunit (RTA) as a template, Rosetta-based homology modeling coupled with energetic decomposition led us to predict that a single pairwise interaction between Arg29 on V5C1 and Glu67 on RTA was responsible for the difference in ricin toxin binding affinity between V1C7, a weak neutralizer, and V5C1, a moderate neutralizer. This prediction was borne out experimentally: substitution of Arg for Gly at position 29 enhanced V1C7's binding affinity for ricin, whereas the reverse (ie, Gly for Arg at position 29) diminished V5C1's binding affinity by >10 fold. As expected, the V5C1R29G mutant was largely devoid of toxin-neutralizing activity (TNA). However, the TNA of the V1C7G29R mutant was not correspondingly improved, indicating that in the V1C7 family binding affinity alone does not account for differences in antibody function. V1C7 and V5C1, as well as their respective point mutants, recognized indistinguishable epitopes on RTA, at least at the level of sensitivity afforded by hydrogen-deuterium mass spectrometry. The results of this study have implications for engineering therapeutic antibodies because they demonstrate that even subtle differences in epitope specificity can account for important differences in antibody function.
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Affiliation(s)
- Andrea Bazzoli
- Center for Computational Biology, University of Kansas, Lawrence, Kansas, 66045.,Computational Chemical Biology Core, University of Kansas, Lawrence, Kansas, 66047
| | - David J Vance
- New York State Department of Health, Division of Infectious Diseases, Wadsworth Center, Albany, New York, 12208
| | | | - Yinghui Rong
- New York State Department of Health, Division of Infectious Diseases, Wadsworth Center, Albany, New York, 12208
| | - Siva Krishna Angalakurthi
- Department of Pharmaceutical Chemistry, Macromolecule and Vaccine Stabilization Center, University of Kansas, Lawrence, Kansas, 66045
| | - Ronald T Toth
- Department of Pharmaceutical Chemistry, Macromolecule and Vaccine Stabilization Center, University of Kansas, Lawrence, Kansas, 66045
| | - C Russell Middaugh
- Department of Pharmaceutical Chemistry, Macromolecule and Vaccine Stabilization Center, University of Kansas, Lawrence, Kansas, 66045
| | - David B Volkin
- Department of Pharmaceutical Chemistry, Macromolecule and Vaccine Stabilization Center, University of Kansas, Lawrence, Kansas, 66045
| | - David D Weis
- Department of Chemistry, University of Kansas, Lawrence, Kansas, 66045
| | - John Karanicolas
- Center for Computational Biology, University of Kansas, Lawrence, Kansas, 66045.,Department of Molecular Biosciences, University of Kansas, Lawrence, Kansas, 66045.,Program in Molecular Therapeutics, Fox Chase Cancer Center, Philadelphia, Pennsylvania, 19111
| | - Nicholas J Mantis
- New York State Department of Health, Division of Infectious Diseases, Wadsworth Center, Albany, New York, 12208
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16
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Rong Y, Van Slyke G, Vance DJ, Westfall J, Ehrbar D, Mantis NJ. Spatial location of neutralizing and non-neutralizing B cell epitopes on domain 1 of ricin toxin's binding subunit. PLoS One 2017; 12:e0180999. [PMID: 28700745 PMCID: PMC5507285 DOI: 10.1371/journal.pone.0180999] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2017] [Accepted: 06/23/2017] [Indexed: 12/14/2022] Open
Abstract
Ricin toxin’s binding subunit (RTB) is a galactose-/N-acetylgalactosamine (Gal/GalNac)-specific lectin that mediates uptake and intracellular trafficking of ricin within mammalian cells. Structurally, RTB consists of two globular domains, each divided into three homologous sub-domains (α, β, γ). In this report, we describe five new murine IgG monoclonal antibodies (mAbs) against RTB: MH3, 8A1, 8B3, LF1, and LC5. The mAbs have similar binding affinities (KD) for ricin holotoxin, but displayed a wide range of in vitro toxin-neutralizing activities. Competition ELISAs indicate that the two most potent toxin-neutralizing mAbs (MH3, 8A1), as well as one of the moderate toxin-neutralizing mAbs (LF1), recognize distinct epitopes near the low affinity Gal recognition domain in RTB subdomain 1α. Evaluated in a mouse model of systemic ricin challenge, all five mAbs afforded some benefit against intoxication, but only MH3 was protective. However, neither MH3 nor 24B11, another well-characterized mAb against RTB subdomain 1α, could passively protect mice against a mucosal (intranasal) ricin challenge. This is in contrast to SylH3, a previously characterized mAb directed against an epitope near RTB’s high affinity Gal/GalNac recognition element in sub-domain 2γ, which protected animals against systemic and mucosal ricin exposure. SylH3 was significantly more effective than MH3 and 24B11 at blocking ricin attachment to host cell receptors, suggesting that mucosal immunity to ricin is best imparted by antibodies that target RTB’s high affinity Gal/GalNac recognition element in subdomain 2γ, not the low affinity Gal recognition domain in subdomain 1α.
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Affiliation(s)
- Yinghui Rong
- Division of Infectious Disease, Wadsworth Center, New York State Department of Health, Albany, New York, United States of America
| | - Greta Van Slyke
- Division of Infectious Disease, Wadsworth Center, New York State Department of Health, Albany, New York, United States of America
| | - David J. Vance
- Division of Infectious Disease, Wadsworth Center, New York State Department of Health, Albany, New York, United States of America
| | - Jennifer Westfall
- Division of Infectious Disease, Wadsworth Center, New York State Department of Health, Albany, New York, United States of America
| | - Dylan Ehrbar
- Division of Infectious Disease, Wadsworth Center, New York State Department of Health, Albany, New York, United States of America
| | - Nicholas J. Mantis
- Division of Infectious Disease, Wadsworth Center, New York State Department of Health, Albany, New York, United States of America
- Department of Biomedical Sciences, University at Albany School of Public Health, Albany, New York, United States of America
- * E-mail:
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17
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Rudolph MJ, Vance DJ, Cassidy MS, Rong Y, Mantis NJ. Structural Analysis of Single Domain Antibodies Bound to a Second Neutralizing Hot Spot on Ricin Toxin's Enzymatic Subunit. J Biol Chem 2017; 292:872-883. [PMID: 27903650 PMCID: PMC5247660 DOI: 10.1074/jbc.m116.758102] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2016] [Revised: 11/10/2016] [Indexed: 12/15/2022] Open
Abstract
Ricin toxin is a heterodimer consisting of RTA, a ribosome-inactivating protein, and RTB, a lectin that facilitates receptor-mediated uptake into mammalian cells. In previous studies, we demonstrated that toxin-neutralizing antibodies target four spatially distinct hot spots on RTA, which we refer to as epitope clusters I-IV. In this report, we identified and characterized three single domain camelid antibodies (VHH) against cluster II. One of these VHHs, V5E1, ranks as one of the most potent ricin-neutralizing antibodies described to date. We solved the X-ray crystal structures of each of the three VHHs (E1, V1C7, and V5E1) in complex with RTA. V5E1 buries a total of 1,133 Å2 of surface area on RTA and makes primary contacts with α-helix A (residues 18-32), α-helix F (182-194), as well as the F-G loop. V5E1, by virtue of complementarity determining region 3 (CDR3), may also engage with RTB and potentially interfere with the high affinity galactose-recognition element that plays a critical role in toxin attachment to cell surfaces and intracellular trafficking. The two other VHHs, E1 and V1C7, bind epitopes adjacent to V5E1 but display only weak toxin neutralizing activity, thereby providing structural insights into specific residues within cluster II that may be critical contact points for toxin inactivation.
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Affiliation(s)
- Michael J Rudolph
- From the New York Structural Biology Center, New York, New York 10027,
| | - David J Vance
- the Division of Infectious Diseases, Wadsworth Center, New York State Department of Health, Albany, New York 12208, and
| | - Michael S Cassidy
- From the New York Structural Biology Center, New York, New York 10027
| | - Yinghui Rong
- the Division of Infectious Diseases, Wadsworth Center, New York State Department of Health, Albany, New York 12208, and
| | - Nicholas J Mantis
- the Division of Infectious Diseases, Wadsworth Center, New York State Department of Health, Albany, New York 12208, and
- the Department of Biomedical Sciences, University at Albany, Albany, New York 12201
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18
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Rudolph MJ, Vance DJ, Cassidy MS, Rong Y, Shoemaker CB, Mantis NJ. Structural analysis of nested neutralizing and non-neutralizing B cell epitopes on ricin toxin's enzymatic subunit. Proteins 2016; 84:1162-72. [PMID: 27159829 DOI: 10.1002/prot.25062] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2016] [Revised: 03/31/2016] [Accepted: 04/28/2016] [Indexed: 11/10/2022]
Abstract
In this report, we describe the X-ray crystal structures of two single domain camelid antibodies (VH H), F5 and F8, each in complex with ricin toxin's enzymatic subunit (RTA). F5 has potent toxin-neutralizing activity, while F8 has weak neutralizing activity. F5 buried a total of 1760 Å(2) in complex with RTA and made contact with three prominent secondary structural elements: α-helix B (Residues 98-106), β-strand h (Residues 113-117), and the C-terminus of α-helix D (Residues 154-156). F8 buried 1103 Å(2) in complex with RTA that was centered primarily on β-strand h. As such, the structural epitope of F8 is essentially nested within that of F5. All three of the F5 complementarity determining regions CDRs were involved in RTA contact, whereas F8 interactions were almost entirely mediated by CDR3, which essentially formed a seventh β-strand within RTA's centrally located β-sheet. A comparison of the two structures reported here to several previously reported (RTA-VH H) structures identifies putative contact sites on RTA, particularly α-helix B, associated with potent toxin-neutralizing activity. This information has implications for rational design of RTA-based subunit vaccines for biodefense. Proteins 2016; 84:1162-1172. © 2016 Wiley Periodicals, Inc.
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Affiliation(s)
| | - David J Vance
- Division of Infectious Diseases, New York State Department of Health, Wadsworth Center, Albany, New York, 12208
| | | | - Yinghui Rong
- Division of Infectious Diseases, New York State Department of Health, Wadsworth Center, Albany, New York, 12208
| | - Charles B Shoemaker
- Tufts Cummings School of Veterinary Medicine, North Grafton, Massachusetts, 01536
| | - Nicholas J Mantis
- Division of Infectious Diseases, New York State Department of Health, Wadsworth Center, Albany, New York, 12208.,Department of Biomedical Sciences, University at Albany, Albany, New York, 12201
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19
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Greene CJ, Hu JC, Vance DJ, Rong Y, Mandell L, King-Lyons N, Masso-Welch P, Mantis NJ, Connell TD. Enhancement of humoral immunity by the type II heat-labile enterotoxin LT-IIb is dependent upon IL-6 and neutrophils. J Leukoc Biol 2016; 100:361-9. [PMID: 27059843 DOI: 10.1189/jlb.3a0415-153rr] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2015] [Accepted: 03/23/2016] [Indexed: 11/24/2022] Open
Abstract
LT-IIb, a type II heat-labile enterotoxin produced by Escherichia coli, is a potent intradermal adjuvant that enhances immune responses to coadministered antigens. Although the immune mechanisms that promote this augmented immune response have not been well defined, prior intradermal immunization experiments suggested that early cellular and immunomodulatory events at the site of immunization modulated the augmentation of antigen-specific immune responses by LT-IIb. To investigate that hypothesis, mice were intradermally immunized with a recombinant ricin vaccine, a prospective toxin subunit antigen, in the presence and absence of LT-IIb. Analysis of tissue-fluid collection, coupled with histologic sections from the site of intradermal immunization, revealed that a single dose of LT-IIb induced local production of interleukin 6 and promoted a regional infiltration of neutrophils. The adjuvant effects of LT-IIb were abrogated in interleukin 6-deficient mice and when mice were depleted of neutrophils by pretreatment with anti-Ly6G. Overall, these data firmly demonstrated that LT-IIb, when used as an intradermal adjuvant, recruits neutrophils and is a potent rapid inducer of interleukin 6.
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Affiliation(s)
- Christopher J Greene
- Department of Microbiology and Immunology, University at Buffalo, State University of New York, Buffalo, New York, USA; Witebsky Center for Microbial Pathogenesis and Immunology, University at Buffalo, State University of New York, Buffalo, New York, USA
| | - John C Hu
- Department of Microbiology and Immunology, University at Buffalo, State University of New York, Buffalo, New York, USA; Witebsky Center for Microbial Pathogenesis and Immunology, University at Buffalo, State University of New York, Buffalo, New York, USA
| | - David J Vance
- Division of Infectious Disease, Wadsworth Center, New York State Department of Health, Albany, New York, USA; and
| | - Yinghui Rong
- Division of Infectious Disease, Wadsworth Center, New York State Department of Health, Albany, New York, USA; and
| | - Lorrie Mandell
- Department of Microbiology and Immunology, University at Buffalo, State University of New York, Buffalo, New York, USA; Witebsky Center for Microbial Pathogenesis and Immunology, University at Buffalo, State University of New York, Buffalo, New York, USA
| | - Natalie King-Lyons
- Department of Microbiology and Immunology, University at Buffalo, State University of New York, Buffalo, New York, USA; Witebsky Center for Microbial Pathogenesis and Immunology, University at Buffalo, State University of New York, Buffalo, New York, USA
| | - Patricia Masso-Welch
- Department of Biotechnical and Clinical Laboratory Sciences, University at Buffalo, State University of New York, Buffalo, New York, USA
| | - Nicholas J Mantis
- Division of Infectious Disease, Wadsworth Center, New York State Department of Health, Albany, New York, USA; and Department of Biomedical Sciences, University at Albany, Albany, New York
| | - Terry D Connell
- Department of Microbiology and Immunology, University at Buffalo, State University of New York, Buffalo, New York, USA; Witebsky Center for Microbial Pathogenesis and Immunology, University at Buffalo, State University of New York, Buffalo, New York, USA;
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20
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Abstract
The past several years have seen major advances in the development of a safe and efficacious ricin toxin vaccine, including the completion of two Phase I clinical trials with two different recombinant A subunit (RTA)-based vaccines: RiVax™ and RVEc™ adsorbed to aluminum salt adjuvant, as well as a non-human primate study demonstrating that parenteral immunization with RiVax elicits a serum antibody response that was sufficient to protect against a lethal dose aerosolized ricin exposure. One of the major obstacles moving forward is assessing vaccine efficacy in humans, when neither ricin-specific serum IgG endpoint titers nor toxin-neutralizing antibody levels are accepted as definitive predictors of protective immunity. In this review we summarize ongoing efforts to leverage recent advances in our understanding of RTA-antibody interactions at the structural level to develop novel assays to predict vaccine efficacy in humans.
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Affiliation(s)
- David J Vance
- a Division of Infectious Disease, Wadsworth Center, New York State Department of Health , Albany , NY , USA
| | - Nicholas J Mantis
- a Division of Infectious Disease, Wadsworth Center, New York State Department of Health , Albany , NY , USA.,b Department of Biomedical Sciences , University at Albany , Albany , NY , USA
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21
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Hassett KJ, Vance DJ, Jain NK, Sahni N, Rabia LA, Cousins MC, Joshi S, Volkin DB, Middaugh CR, Mantis NJ, Carpenter JF, Randolph TW. Glassy-state stabilization of a dominant negative inhibitor anthrax vaccine containing aluminum hydroxide and glycopyranoside lipid A adjuvants. J Pharm Sci 2015; 104:627-39. [PMID: 25581103 DOI: 10.1002/jps.24295] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2014] [Revised: 10/11/2014] [Accepted: 10/28/2014] [Indexed: 01/14/2023]
Abstract
During transport and storage, vaccines may be exposed to temperatures outside of the range recommended for storage, potentially causing efficacy losses. To better understand and prevent such losses, dominant negative inhibitor (DNI), a recombinant protein antigen for a candidate vaccine against anthrax, was formulated as a liquid and as a glassy lyophilized powder with the adjuvants aluminum hydroxide and glycopyranoside lipid A (GLA). Freeze-thawing of the liquid vaccine caused the adjuvants to aggregate and decreased its immunogenicity in mice. Immunogenicity of liquid vaccines also decreased when stored at 40°C for 8 weeks, as measured by decreases in neutralizing antibody titers in vaccinated mice. Concomitant with efficacy losses at elevated temperatures, changes in DNI structure were detected by fluorescence spectroscopy and increased deamidation was observed by capillary isoelectric focusing (cIEF) after only 1 week of storage of the liquid formulation at 40°C. In contrast, upon lyophilization, no additional deamidation after 4 weeks at 40°C and no detectable changes in DNI structure or reduction in immunogenicity after 16 weeks at 40°C were observed. Vaccines containing aluminum hydroxide and GLA elicited higher immune responses than vaccines adjuvanted with only aluminum hydroxide, with more mice responding to a single dose.
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Affiliation(s)
- Kimberly J Hassett
- Department of Chemical and Biological Engineering, Center for Pharmaceutical Biotechnology, University of Colorado, Boulder, Boulder, Colorado, 80303
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Vance DJ, Rong Y, Brey RN, Mantis NJ. Combination of two candidate subunit vaccine antigens elicits protective immunity to ricin and anthrax toxin in mice. Vaccine 2015; 33:417-21. [PMID: 25475957 PMCID: PMC4274239 DOI: 10.1016/j.vaccine.2014.11.036] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2014] [Revised: 09/30/2014] [Accepted: 11/17/2014] [Indexed: 10/24/2022]
Abstract
In an effort to develop combination vaccines for biodefense, we evaluated a ricin subunit antigen, RiVax, given in conjunction with an anthrax protective antigen, DNI. The combination led to high endpoint titer antibody response, neutralizing antibodies, and protective immunity against ricin and anthrax lethal toxin. This is a natural combination vaccine, since both antigens are recombinant subunit proteins that would be given to the same target population.
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Affiliation(s)
- David J Vance
- Division of Infectious Disease, Wadsworth Center, New York State Department of Health, Albany, NY, USA
| | - Yinghui Rong
- Division of Infectious Disease, Wadsworth Center, New York State Department of Health, Albany, NY, USA
| | | | - Nicholas J Mantis
- Division of Infectious Disease, Wadsworth Center, New York State Department of Health, Albany, NY, USA; Department of Biomedical Sciences, University at Albany, Albany, NY, USA.
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Mukherjee J, Tremblay J, Sheoran A, Schmidt D, Vance DJ, Mantis NJ, Moayeri M, Leppla SH, Dmitriev I, Curiel DT, Tzipori S, Shoemaker CB. 148. Variable fragment of heavy chain antibody (VHH)–based neutralizing agents (VNAs) as unconventional and versatile therapeutics for toxin-mediated diseases. Toxicon 2015. [DOI: 10.1016/j.toxicon.2014.11.151] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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Rudolph MJ, Vance DJ, Cheung J, Franklin MC, Burshteyn F, Cassidy MS, Gary EN, Herrera C, Shoemaker CB, Mantis NJ. Crystal structures of ricin toxin's enzymatic subunit (RTA) in complex with neutralizing and non-neutralizing single-chain antibodies. J Mol Biol 2014; 426:3057-68. [PMID: 24907552 PMCID: PMC4128236 DOI: 10.1016/j.jmb.2014.05.026] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2014] [Revised: 05/17/2014] [Accepted: 05/25/2014] [Indexed: 10/25/2022]
Abstract
Ricin is a select agent toxin and a member of the RNA N-glycosidase family of medically important plant and bacterial ribosome-inactivating proteins. In this study, we determined X-ray crystal structures of the enzymatic subunit of ricin (RTA) in complex with the antigen binding domains (VHH) of five unique single-chain monoclonal antibodies that differ in their respective toxin-neutralizing activities. None of the VHHs made direct contact with residues involved in RTA's RNA N-glycosidase activity or induced notable allosteric changes in the toxin's subunit. Rather, the five VHHs had overlapping structural epitopes on the surface of the toxin and differed in the degree to which they made contact with prominent structural elements in two folding domains of the RTA. In general, RTA interactions were influenced most by the VHH CDR3 (CDR, complementarity-determining region) elements, with the most potent neutralizing antibody having the shortest and most conformationally constrained CDR3. These structures provide unique insights into the mechanisms underlying toxin neutralization and provide critically important information required for the rational design of ricin toxin subunit vaccines.
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Affiliation(s)
| | - David J Vance
- Division of Infectious Diseases, Wadsworth Center, New York State Department of Health, Albany, NY 12208, USA
| | - Jonah Cheung
- New York Structural Biology Center, New York, NY 10027, USA
| | | | | | | | - Ebony N Gary
- New York Structural Biology Center, New York, NY 10027, USA
| | - Cristina Herrera
- Division of Infectious Diseases, Wadsworth Center, New York State Department of Health, Albany, NY 12208, USA; Department of Biomedical Sciences, University at Albany, Albany, NY 12201, USA
| | | | - Nicholas J Mantis
- Division of Infectious Diseases, Wadsworth Center, New York State Department of Health, Albany, NY 12208, USA; Department of Biomedical Sciences, University at Albany, Albany, NY 12201, USA.
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25
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Herrera C, Vance DJ, Eisele LE, Shoemaker CB, Mantis NJ. Differential neutralizing activities of a single domain camelid antibody (VHH) specific for ricin toxin's binding subunit (RTB). PLoS One 2014; 9:e99788. [PMID: 24918772 PMCID: PMC4053406 DOI: 10.1371/journal.pone.0099788] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2014] [Accepted: 05/17/2014] [Indexed: 11/18/2022] Open
Abstract
Ricin, a member of the A-B family of ribosome-inactivating proteins, is classified as a Select Toxin by the Centers for Disease Control and Prevention because of its potential use as a biothreat agent. In an effort to engineer therapeutics for ricin, we recently produced a collection of alpaca-derived, heavy-chain only antibody VH domains (VHH or “nanobody”) specific for ricin’s enzymatic (RTA) and binding (RTB) subunits. We reported that one particular RTB-specific VHH, RTB-B7, when covalently linked via a peptide spacer to different RTA-specific VHHs, resulted in heterodimers like VHH D10/B7 that were capable of passively protecting mice against a lethal dose challenge with ricin. However, RTB-B7 itself, when mixed with ricin at a 1∶10 toxin:antibody ratio did not afford any protection in vivo, even though it had demonstrable toxin-neutralizing activity in vitro. To better define the specific attributes of antibodies associated with ricin neutralization in vitro and in vivo, we undertook a more thorough characterization of RTB-B7. We report that RTB-B7, even at 100-fold molar excess (toxin:antibody) was unable to alter the toxicity of ricin in a mouse model. On the other hand, in two well-established cytotoxicity assays, RTB-B7 neutralized ricin with a 50% inhibitory concentration (IC50) that was equivalent to that of 24B11, a well-characterized and potent RTB-specific murine monoclonal antibody. In fact, RTB-B7 and 24B11 were virtually identical when compared across a series of in vitro assays, including adherence to and neutralization of ricin after the toxin was pre-bound to cell surface receptors. RTB-B7 differed from both 24B11 and VHH D10/B7 in that it was relatively less effective at blocking ricin attachment to receptors on host cells and was not able to form high molecular weight toxin:antibody complexes in solution. Whether either of these activities is important in ricin toxin neutralizing activity in vivo remains to be determined.
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Affiliation(s)
- Cristina Herrera
- Division of Infectious Disease, Wadsworth Center, New York State Department of Health, Albany, New York, United States of America
- Department of Biomedical Sciences, University at Albany School of Public Health, Albany, New York, United States of America
| | - David J. Vance
- Division of Infectious Disease, Wadsworth Center, New York State Department of Health, Albany, New York, United States of America
| | - Leslie E. Eisele
- Scientific Cores, Wadsworth Center, New York State Department of Health, Albany, New York, United States of America
| | - Charles B. Shoemaker
- Department of Infectious Disease and Global Health, Tufts Cummings School of Veterinary Medicine, North Grafton, Massachusetts, United States of America
| | - Nicholas J. Mantis
- Division of Infectious Disease, Wadsworth Center, New York State Department of Health, Albany, New York, United States of America
- Department of Biomedical Sciences, University at Albany School of Public Health, Albany, New York, United States of America
- * E-mail:
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Vance DJ, Tremblay JM, Mantis NJ, Shoemaker CB. Stepwise engineering of heterodimeric single domain camelid VHH antibodies that passively protect mice from ricin toxin. J Biol Chem 2013; 288:36538-47. [PMID: 24202178 DOI: 10.1074/jbc.m113.519207] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
In an effort to engineer countermeasures for the category B toxin ricin, we produced and characterized a collection of epitopic tagged, heavy chain-only antibody VH domains (VHHs) specific for the ricin enzymatic (RTA) and binding (RTB) subunits. Among the 20 unique ricin-specific VHHs we identified, six had toxin-neutralizing activity: five specific for RTA and one specific for RTB. Three neutralizing RTA-specific VHHs were each linked via a short peptide spacer to the sole neutralizing anti-RTB VHH to create VHH "heterodimers." As compared with equimolar concentrations of their respective monovalent monomers, all three VHH heterodimers had higher affinities for ricin and, in the case of heterodimer D10/B7, a 6-fold increase in in vitro toxin-neutralizing activity. When passively administered to mice at a 4:1 heterodimer:toxin ratio, D10/B7 conferred 100% survival in response to a 10 × LD50 ricin challenge, whereas a 2:1 heterodimer:toxin ratio conferred 20% survival. However, complete survival was achievable when the low dose of D10/B7 was combined with an IgG1 anti-epitopic tag monoclonal antibody, possibly because decorating the toxin with up to four IgGs promoted serum clearance. The two additional ricin-specific heterodimers, when tested in vivo, provided equal or greater passive protection than D10/B7, thereby warranting further investigation of all three heterodimers as possible therapeutics.
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Affiliation(s)
- David J Vance
- From the Division of Infectious Disease, Wadsworth Center, New York State Department of Health, Albany, New York 12208 and
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Yermakova A, Vance DJ, Mantis NJ. Sub-domains of ricin's B subunit as targets of toxin neutralizing and non-neutralizing monoclonal antibodies. PLoS One 2012; 7:e44317. [PMID: 22984492 PMCID: PMC3439471 DOI: 10.1371/journal.pone.0044317] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2012] [Accepted: 08/01/2012] [Indexed: 12/30/2022] Open
Abstract
The B subunit (RTB) of ricin toxin is a galactose (Gal)−/N-acetylgalactosamine (GalNac)-specific lectin that mediates attachment, entry, and intracellular trafficking of ricin in host cells. Structurally, RTB consists of two globular domains with identical folding topologies. Domains 1 and 2 are each comprised of three homologous sub-domains (α, β, γ) that likely arose by gene duplication from a primordial carbohydrate recognition domain (CRD), although only sub-domains 1α and 2γ retain functional lectin activity. As part of our ongoing effort to generate a comprehensive B cell epitope map of ricin, we report the characterization of three new RTB-specific monoclonal antibodies (mAbs). All three mAbs, JB4, B/J F9 and C/M A2, were initially identified based on their abilities to neutralize ricin in a Vero cell cytotoxicty assay and to partially (or completely) block ricin attachment to cell surfaces. However, only JB4 proved capable of neutralizing ricin in a macrophage apoptosis assay and in imparting passive immunity to mice in a model of systemic intoxication. Using a combination of techniques, including competitive ELISAs, pepscan analysis, differential reactivity by Western blot, as well as affinity enrichment of phage displayed peptides, we tentatively localized the epitopes recognized by the non-neutralizing mAbs B/J F9 and C/M A2 to sub-domains 2α and 2β, respectively. Furthermore, we propose that the epitope recognized by JB4 is within sub-domain 2γ, adjacent to RTB’s high affinity Gal/GalNAc CRD. These data suggest that recognition of RTB’s sub-domains 1α and 2γ are critical determinants of antibody neutralizing activity and protective immunity to ricin.
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Affiliation(s)
- Anastasiya Yermakova
- Division of Infectious Disease, Wadsworth Center, New York State Department of Health, Albany, New York, United States of America
- Department of Biomedical Sciences, University at Albany School of Public Health, Albany, New York, United States of America
| | - David J. Vance
- Division of Infectious Disease, Wadsworth Center, New York State Department of Health, Albany, New York, United States of America
| | - Nicholas J. Mantis
- Division of Infectious Disease, Wadsworth Center, New York State Department of Health, Albany, New York, United States of America
- Department of Biomedical Sciences, University at Albany School of Public Health, Albany, New York, United States of America
- * E-mail:
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